Controller for electric motors.



No. 844,352. PATENTED EER. .19, 1907. y EU. HART. A l' CONTROLLER ECRELECTRIC MOTORS.

APPLICATION FILED .TUNE 12,1905.

2 SHEETS-SHEET l.

W|TNESSES2 INVENTOR ATTORNEY 1H: mmms PzfERs cc., wAsHmaroN, n. c,

PATBNTED FEB. 19.' 1907.

, H. U. HART.

CONTROLLER POB. ELECTRIC MOTORS.

APPLIGATION FILED JUNE l2, 1905.

2 SHEETS-SHEET 2.v

AT'TORNEY Tus Nomus PETERS cc.; wAsmNcmN, n. c.

UNITED STATES ATH@ FFCH.

HARRY U. I-IART, OE LE HAVRE, FRANCE, AssIoNoR To wEsTINoHOUsE ELECTRICa MANUFACTURING COMPANY, A CORPORATION OE PENN- SYLVANIA.

CONTROLLER FOR ELECTRIC MOTORS.

Patented Feb. 19, 1907.

Application filed June 12,1905. Serial N0. 264.836.

T0 all whom it may concern.'

Be it known that I, HARRY U. HART, a citizen of the United States, and aresident of Le Havre, France, have invented a new and useful Improvementin Controllers for Electric Motors, of which the following is aspecification.

My invention relates to controllers for motor-driven vehicles, andespecially to those controllers which are adapted to connect the motorsin a local circuit, thereby converting them into generators for brakingpurposes.

The object of my invention is to provide a controller in which one ormore of the brakingnotches will be serviceable when the reverseswitchoccupies either the forward or reverse position, regardless of thedirection of motion of the vehicle.

In the use ofthe controllers of the prior art that are provided withbraking connections it is necessary to change the position of thereversing-switch if for any reason the direction of rotation of themotor armatures becomes the reverse of that to which the originalposition of the controller corresponds. For instance, if a vehicle isstopped by means of an electric brake during the ascent of a grade andthen, owing to the failure of the motor- Inan to operate the hand-brake,starts backward down the grade, it has heretofore been necessary toreturn the main drum to its off position, change the position of thereversingswitch, and again move the main drum through its brakingpositions in order that the armature and field-magnet windings of themotors may be connected in proper relation to cause the motors tooperate as generators. The motors will not operate as generators if thearmature and field-magnet windings remain connected in the samerelations that obtained previous to the reversal of the direction ofrotation of the armatures, owing to their inherent inability to overcomethe residual magnetism of the field-magnet cores, and thereby effectreversal of magnet polarity.

My invention provides means for so interconnecting the armature andfield-magnet windings of the motors in a local braking-circuit that thedirection of current-How in at least one field-magnet winding may remainunchanged when the direction of rotation of the armatures is reversed.It is dependent in its operation upon the difference that eX- istsnaturally or that may be caused to eX stv between the voltages generatedby the motors when operating as generators. Necessity is thereby avoidedfor reversing the magnetic polarity of the fields of all of the motorsand for operating the reversing-switch in order to obtain brakingconditions when the direction of rotation of the motor-armatureschanges. l

My invention is illustrated in the accompanying drawings, in which-Figure l is a top plan view of a controller constructed in accordancetherewith, the inclosing casing being shown in section. Fig. 2 is adiagrammatic View of a development of the controller of Fig. 1 and itscircuit connections, and Figs. 3 and 4 represent diagrammatically thecircuit conditions when the controller occupies certain of its brakingpositions.

The controller to which my invention may be and has been applied is onethat in its details of construction and mode of operation is verysimilar to that which is fully shown and described in United StatesPatent No. 780,058, granted January 17, 1905, to the WestinghouseElectric & Manufacturing Company as assignee of Thomas S. Perkins, andsince reference may be had thereto only such parts will be here shownand described as may be essential to an understanding of the operationof my invention.

The shaft 1, on which the main drum 2 is mounted, is provided with anindicator wheel or disk, having in its periphery the usual notches o, t,c, d, e, f, g, h, and i, that correspond, respectively, to the powerpositions of the controller-drum, and notches a', b', c, d, e,f, and g,that correspond, respectively, to the braking positions of thecontroller. Aroller 4, that is mounted in the end of a pawl 5, is drawninto engagement with the periphery' of the indicator wheel by means of acoil-spring 6, as is usual in apparatus of this character.

For the purpose of automatically throwing the reversing-switch 7 whenthe controller passes from the first power position A to the firstbraking position A, I provide the Wheel 3 with a cam-groove, comprisingtwo concentric ortions 8 and 9 at diiferent distances from the shaft 1,and an approximately straight portion 1 O, connecting the concentricportions 8 and 9, and in order to automatically throw thereversing-switch from positions F and R to positions M and N,respectively', when the main drum is moved from position Fl to positionG', the wheel 3 is further provided with a grooved portion 11, thatadjoins the grooved portion 9 and is more remote from the shaft thansaid grooved portion 9. Operating in this camgroove 8 9 10 11 is aroller 12, which 1s mounted upon an arm 13, the inner end of which ispivoted to the controller frame at 14.

- 22 which are respectively in position to cooperate with the lateralslots 18 and 19 in thehead 16 of the lever-arm 15. In order to throw thehead 16 to the one side ofthe other for the purpose of engagement withthe one or the other of the studs 21 and 22, I provide a lever 23, oneend of which is provided with three notches 24, 25, and 26. The pawl 27carries at its free end aroller 28, that engages with one of the notches24, 25, and 26 and is pressed into engagement therewith by the spring 6,one end of which is fastened to an extension 29 of the pawl-lever 27,thereby tending to hold the lever 23 in whichever position it maybeadjusted. The lever 23 is provided at the end opposite the notches witha stud 30, which is located in the slot 17 -in the end of the head 16,and the lever 23 is o erated by means of a suitable handle (not siown)attached to the shaft 31, on which the lever 23 is mounted.

When the roller 28 of the pawl 27 is in the central notch`25 of thelever 23, the mainl controller-drum is locked against movement by meansof the slots 18 and 194 and the studs 21 and 22, and this position ofthe parts corresponds to zero or off position of the controller-drum.

In order to throw the reversing-switch in either direction to insureeither forward or backward movement of the vehicle, the lever 23 iscorrespondingly moved by the reversingswitch handle, and it in turnthrows the head 16 either inward or outward, so that one of the studs 21and 22 is in the corresponding lateral slot in the head 16 and the otheris free therefrom. The rotation of the main controller-drum then serves,through the cam-groove 8 9 10 11 and coperating mechanism, to throw thereversing-switch in the direction desired. As soon as thereversing-switch is thrown by this means so One end of an arm 15 ispivotally attached to the outer end of arm 13 and prothat the 'stud 2Gor the stud 21, which is free from the corresponding slot in the head 16is moved out of ahnement therewith the reversing-switch is obviouslylocked against any other movement so long as the stud or roller 12 is inengagement with either of the concentric portions of the cam-groove 8 910111.

If the main drum 2 occupies any of the braking positions from A to F',inclusive, and the motors governed by the controller come to a stop andthen reverse their direction of rotation, the controller drum should bemoved to position G in order to so connect the field-magnet andarmature-windings as to convert the motors into generators.

When the controller occupies any of the braking positions exceptposition G', the roller 12 is located in the concentric portion 9 of thecam-groove; but when the main drum is thrown to the position G theroller 12 is caused to occupy the portion 11 of the cam-groove which isfarthest removed from the shaft 1. This operation causes thereversing-switch to be moved from position R. or position F (see'Fig. 2)to the one or the other 'of positions M and N, according to the originalposition occupied by the reversingswitch.

In the first braking position A of the controller-drum 2 thereversing-switch may occupy either position F or position R, theconditions of the circuits being as represented in Fig., 3, in which themotors 32 and 33 are connected in parallel relation with each other andin series with a brake-magnet coil 34 and a resistance 35, that is cutout of circuit progressively in the succeeding positions. An equalizingconnection is also made between the terminals of the armature-windingsthat are connected to the terminals of their respective field-magnetwindings, and a blowout coil 36 may be also included in the circuit. Thedirection of the current-how is from the armature 37 throughfield-magnet winding 40, brake-magnet winding 34, and resistance 35, andalso from armature 39 through field-magnet winding 38, brakemagnetwinding 34, and resistance 35 in the direction of the arrows.

When the main drum is moved to the position G', the reversing-switch ismoved to either position M or position N, and the conditions of thecircuits may be as illustrated in Fig. 4. The direction of thecurrent-How may be assumed to be from armature 37,

through armature 39 and field-magnet windings 40 and 38, and alsothrough brake-magnet winding 34 in parallel to the circuit` through thearmature 39 and field-magnet winding 40, all as indicated by the arrows.Since the direction of the current in the fieldmagnet winding 40 remainsthe same as before the reversal of direction of rotation of thearmatures, the motor 32 will be con- IIO verted into a generator and thecurrent generated will overcome the residual magnetism in thefield-magnet oi the motor 33 and it, too, will be converted into agenerator for braking purposes. act as a generator and cause reversal ofheld polarity in the other motor, according to which generates thehighest voltage when operating as a generator.

The eifectiveness of the winding 34 as a brake-setting means when. thecircuits are as shown in Fig. 4 depends mainly -upon its resistance; butthe desiredv braking effect is not necessarily dependent upon thebrakemagnet, since the motors are connected in series in a local circuitand may therefore be relied upon when operating as generators toproperly brake the vehicle upon which they are mounted, even though thebrake-magnet is inactive. v

The controller as here illustrated and described is intended foremployment in connection with equipments having brake-setting magnets,though evidently it may be employed with brakes of the rheostatic type,in which the motors are simply converted into generators and the amountof resistance in the circuit varied. i

I claim as my invention- 1. The combination with an electricalsupply-circuit, two or more electric motors tle armature andfield-magnet windings oi each of which are normally series-connected,and an electrically-operated braking device, of means tor connecting themotors with and disconnecting them from the supply-circuit and forconnecting them in a closed circuit having an equalizing connection fornormal braking, and means for connecting the armature-windings of themotors respectively in series with the iield-magnet windings of adjacentmotors, without an equalizing connection for reverse braking.

2. The combination with an electrical supply-circuit, two or moreelectric motors the armature andiield-magnet windings of each of whichare normally series-connected, and an electrically-operated brakingdevice, of means for connecting the motors with and disconnecting themfrom the supply-circuit and for connecting them in a closed circuit, andmeans Jfor interconnecting the armature and ieldmagnet windings of themotors so that the direction otcurrent-tlow in at least one fieldmagnetwinding remains unchanged it the direction of rotation of the armaturesis reversed.

3. The combination with an electrical supply-circuit and two or moreelectric motors the armature and field-magnet windings of each of whichare normally series-connected, of means for connecting the motors withand disconnecting them trom the supply-circuit and for connecting theminparallel in a closed circuit for normal braking, and means forconnecting the armature windings of the mo- Either motor may firstv torsrespectivelyin series with the field-mag.- net windings of adjacentmotors for reverse braking.

4. rlhe combination with an electrical supply-circuit, and two or moreelectric motors the armature and held-magnet windings of each of whichare normally series-connected,

y of means for connecting the motors with and disconnecting them fromthe supply-circuit and tor connecting them in parallel in a closedcircuit for normal braking, and means for interconnecting the armatureand ieldmagnet windings oi" the motors so that the direction ofcurrent-flow in at least one iieldmagnet winding remains unchanged whenthe direction of rotation of the armatures is re- T'ersed.

5. The combination with an electric supjly-circuit and two or moreelectric motors the armature and field-magnet windings of each of whichare normally series-connected, of a controller comprising a main drumand a reversing-drum, means for automatically throwing thereversing-switch as the main drum moves from r ower 1i ositionto braking'[osition and vice versa, and means for connecting the motors inparallel in a closed circuit for normal braking and means for connectingthe armature-windings respectively in series with field-magnet windingsof adj acent motors for reverse braking.

6. The combination with an electrical suprly-circuit and two or moreelectric motors the armature and field-magnet windings of each of whichare normally series-connected, of a controller com'l rising a main drumand a reversing-drum, means for automatically throwing thereversing-switch as the main drum moves from 'p ower position to braking'position and vice versa, 'and means for interconnecting the armatureand field-magnet windings of the motors in one of the braking r ositionsso that the direction of current-flow in at least one held-magnetwinding remains unchanged when .the direction of rotation of thearmatures is reversed.

7. The combination with an electrical sup- 1f ly-circuit, and two ormore electric motors at least one of which has a higher electromotiveforce than the other or others when driven as a generator, the armatureand fieldmagnet windings of each of said motors being normallyseries-connected, of a controller comprising a main drum and areversingswitch, means for automatically throwing the reversing-switchas the main drum moves from the '1; ower position to braking position toconnect the motors in parallel in a closed circuit for normal brakingand means for moving the reversing-switch to another position to connectthe armature-windings respectively in series with the field-magnetwindings of adjacent motors for reverse braking.

8. The combination with an electrical sup- IOO IIO

ISO

ply-circuit, two or more electric motors the armature and ield-magnetwindings of each of which are normally series-connected7 and anelectrically-operated braking device, of a controller comprising a maindrum and a 'reversing-switch, means for automatically throwing thereversing-switch as the main drum moves from power 'position to brakingposition and vice versa, and means for so interconnecting the armatureand field-magnet windings of the motors in a closed circuit with thebraking device that the direction of current-How in at least oneield-magnet winding remains unchanged when the direction of rotation ofthe armatures is reversed.

9. The combination with an electric supply-circuit and two or moreelectric motors thearmature and field-magnet windings of each of whichare normally series-connected7 of a controller comprising a main drumand a reversing drum7 means for automatically throwing thereversing-switch as the main drum moves from power 'position to brakingposition and vice versa, and means for automatically eilectin'g furthermovement of the reversing-switch as the main drum moves from a givenposition to another.

10. The combination with an electric supply-circuit and two or moreelectric motors the armature and field-magnet windings of each of whichare normally series-connected, of a controller comprising a main drumand a reversing4drum, i means for automatically throwing thereversing-switch as the main drum moves from power position to brakingposition and vice versa, and means for automatically effecting furthermovement of the reversing-switch as the main drum moves.

from a given position to another whereby the motors are connected in aclosed circuit with their armature-windings respectively in series withfield-magnet windings of adjacent motors.

11. The combination with a main drum and a reversing-switch, of meansfor automatically throwing thc reversing-switch as the main drum movesfrom a given position to another position and vice versa, and means forautomatically eecting further movement of the reversing-switch as themain drum moves from another given position to the next and vice versa.

In testimony whereof I have hereunto subscribed my name this 9th day ofJune, 1905.

. HARRY' U. HART. Witnesses:

OTTO S. SCHAIRER, BIRNEY HINEs.

